Snap the PIP window to the left or right edge after pinch resize

Restrict the PIP resize to the left and right edges only,
instead of allowing the top or bottom edges as snap targets.

Bug: 186610221
Test: pinch to resize and let go at the center top or bottom
edge - verify it snaps to either side of the screen

Change-Id: Ifbc96fddc000ccb2ae344755a9276f24e67d4571
2 files changed